ER4043 is a general purpose type aluminum welding wire. It is one of the oldest and most widely used welding and brazing alloys. This aluminum alloy contains silicon additives, which result in improved fluidity (wetting action) of the weld pool and also produces a weld less sensitive to cracking. Its bright weld finish makes it a popular choice of welders. ER4043 can be used to weld various grades of aluminum.